NAG Library Manual, Mark 29.3
```    Program f07hrfe

!     F07HRF Example Program Text

!     Mark 29.3 Release. NAG Copyright 2023.

!     .. Use Statements ..
Use nag_library, Only: nag_wp, x04dff, zpbtrf
!     .. Implicit None Statement ..
Implicit None
!     .. Parameters ..
Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
Integer                          :: i, ifail, info, j, kd, ldab, n
Character (1)                    :: uplo
!     .. Local Arrays ..
Complex (Kind=nag_wp), Allocatable :: ab(:,:)
Character (1)                    :: clabs(1), rlabs(1)
!     .. Intrinsic Procedures ..
Intrinsic                        :: max, min
!     .. Executable Statements ..
Write (nout,*) 'F07HRF Example Program Results'
!     Skip heading in data file
ldab = kd + 1
Allocate (ab(ldab,n))

!     Read A from data file

If (uplo=='U') Then
Do i = 1, n
End Do
Else If (uplo=='L') Then
Do i = 1, n
End Do
End If

!     Factorize A
!     The NAG name equivalent of zpbtrf is f07hrf
Call zpbtrf(uplo,n,kd,ab,ldab,info)

Write (nout,*)
Flush (nout)
If (info==0) Then

!       Print factor

!       ifail: behaviour on error exit
!              =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
ifail = 0
If (uplo=='U') Then

Call x04dff(n,n,0,kd,ab,ldab,'Bracketed','F7.4','Factor','Integer',  &
rlabs,'Integer',clabs,80,0,ifail)

Else If (uplo=='L') Then

Call x04dff(n,n,kd,0,ab,ldab,'Bracketed','F7.4','Factor','Integer',  &
rlabs,'Integer',clabs,80,0,ifail)

End If

Else
Write (nout,*) 'A is not positive definite'
End If

End Program f07hrfe
```